The present invention relates to a picture image position setting apparatus useful in partial copying, in picture transmitting or in electronic editing. When electronically editing, such as for example transmitting or copying an original document with an unnecessary region thereof cut off or, transferring or copying a specific region of an original document to another region, a picture image position setting apparatus is used for causing the system to recognize the above-mentioned regions. A picture image position setting apparatus is known of the type in which the coordinate of the above-mentioned region of the original document is inputted by using number keys. In such an apparatus, however, there is a problem in that not only the number keys and a data processing device annexed to the keys are required but also, the operator is apt to make mistakes during the inputting operation.
FIG. 1 shows a conventional picture image position setting apparatus in which a desired region of an original document can be directly designated on a platen. The moving direction of a linear reading element 1 such as a linear image sensor on a platen 2 (subscanning direction) is represented by X and the direction perpendicular to the direction X is represented by Y (main scanning direction). The picture image position setting apparatus is provided with cursors 3, 4, 5, and 6 positioned close to and outside the platen 1 for performing positioning operations in the X and Y directions. The cursors 3 and 4 disposed movably in the X-direction are respectively registered with the starting and end points in the X-direction in a designated region 7 which is indicated by oblique lines on the original document in the drawing. The other two cursors 5 and 6 disposed movably in the Y-direction are respectively registered with the starting and end points in the Y-direction in the designated region 7.
When the X-direction cursors 3 and 4 are moved for the operation of designating the boundaries of the region not-shown detector elements such as micro switches or reed switches move following the cursors 3 and 4 to be properly positioned at the starting and end points. In the reading operation, these detector elements serve to detect the time when the reading element 1 passes by the starting and end points in the X-direction on the region 7 to provide these starting and end points as inputs to the system.
When the Y-direction cursors 5 and 6 are moved for the region designating operation, on the other hand, two brushes 9A and 9B of a slide resistor 9 shown in FIG. 2 move following the cursors 5 and 6 to be respectively positioned at points corresponding to the starting and end positions in the Y-direction defining boundaries for the region 7. The voltages corresponding to the positions obtained as a result are amplified by amplifiers 11 and 12 and then converted into digital values by A/D converters 13 and 14. These ditigal values are inputted into the system as positional information with respect to the starting and end positions in the Y-direction.
In such a conventional picture image position setting apparatus, since the slide resistor 9 is used, a problem is poor accuracy in positioning in the Y-direction (main scanning direction) because of scatter of the characteristic of the slide resistor and/or an abrupt change in the local resistance value thereof. There has been also a drawback that an A/D converter is required for converting the output voltage of the variable resistor 9 into a digital value, resulting in increase in cost of the apparatus.